1. Field of the Invention
This invention relates to heat exchangers and particularly to a heat exchanger having tubes which are arranged in a latticed pattern and serve to conduct the medium that is to be heated or cooled, the ends of the tubes being held in end walls, and another medium for heat exchange is flowing through the exchanger transversely to the longitudinal direction of the tubes.
Apart from a variety of applications of exchangers of the class described the present invention contemplates utilization of such a heat exchanger with a vertically moving compact bed of heat-transfer media, for example, in the recovery of heat from shale ashes in a process for the continuous retorting of oil shale or for a recuperative heating of granular materials by a gas flowing through the exchanger.
2. Description of the Prior Art
A heat exchanger of the class described is disclosed in U.S. Pat. No. 3,483,920. The heat exchanger comprises tubes arranged in side-by-side planes and serving to conduct a fluid for heat exchange, the tubes in one plane being transverse to those of the other plane. The ends of the tubes are held in side walls of a frame open at two sides transverse to the side walls to form an inlet and outlet for the medium that is to be heated or cooled. The frame is enclosed by a housing having an inlet and outlet for the fluid for heat exchange. The frame is engaged with the housing to form with the housing walls and the side walls of the frame a collector and a distribution chambers intercommunicating via the tubes to provide a flow path for the fluid for heat exchange. One embodiment comprises the frame and the housing held together by means of W-shaped holders, which serve as partitions to divide the housing inner space into a collector and a distribution chambers. In this embodiment the frame holding the tubes is box-shaped while the housing is of a drum-type construction.
The prior-art exchanger provides a flow path for but only one fluid. To heat or cool more than one fluid flow simultaneously it is necessary to use a corresponding number of heat exchangers, which naturally leads to extra floor for the exchangers and if use is made of a building-block exchanger units, they each still have dimensions that are to be considered.
The prior-art exchanger is constructed for two media in heat exchange, namely, a gas and liquid, which gas and liquid may be both a heated or cooled medium, and a gas is conducted through the frame and a liquid along the flow path defined by the collector and the distribution chambers and by the tubes. The flow path defined by the collector and the distribution chambers and by the tubes when used for conducting a gas at a high speed in the heat exchanger constructed according to the teachings of th U.S. Pat. No. 3,483,920 causes an uneven distribution of the gas among the tubes and, consequently, an unsatisfactory heat exchange, since the cross-sectional areas of both the collector and the distribution chambers is small as compared to that of the tubes. This problem is of particular importance in the case of utilizing the prior-art exchanger with a vertically moving compact bed of heat-transfer media, for example, in the recovery of heat from shale ashes in a process for the continuous retorting of oil shale.